Old German organ-builders sometimes used the prefix Aequal
to indicate a stop of unison (8') pitch. When used alone, it indicated
an 8' Principal.
Wedgwood lists the name Chormass as a synonym for Aequal;
Adlung writes:
“[Principal] is also called Aequalprincipal because it matches the range
of the human voice. It is likewise called Chormassprincipal” and
“Chormass is probably understood to be the same as 8'
because it has the same pitch as the human voice”.